The activity or effectiveness of hair shaping preparations is based mainly on the inclusion therein of an agent for softening and relaxing the keratin protein present in hair by reducing the disulfide linkages of keratin. The hair fiber is wound on rods to achieve the desired waving effect or manipulated into a straightened condition and allowed to remain wetted with the reducing lotion for a desired period, after which the reducing lotion is rinsed off and finally oxidized with a neutralizing solution or air oxidized.
Basically, hair is softened and swelled by rupture of disulfide bonds present in the cystine component of keratin by the use of a mild alkaline reducing agent. Cleavage of at least some of the disulfide bonding to form the corresponding cysteine residue is necessary to allow for molecular rearrangement which takes place during the hair fiber molding operation. The reductive fission of hair disulfides qenerally causes reddening of the scalp area and damage to the hair fiber, particularly hair which has been bleached, tinted or otherwise damaged. Current hair structure altering lotions which provide relaxation of imposed stress include aqueous solutions of alkaline mercapto compounds, sulfites or bisulfites at a pH of between 7 and 9.5. In order to obtain a permanent effect, particularly in hair straightening, it is often necessary to introduce the active agent in relatively high concentration with the result that the reducing lotion is provided at almost the limit of its physiological compatability or tolerability.
Damage to hair is increased where heat waving, as opposed to cold waving, is employed. Of the reducing agents currently in use, the thioglycolates or thioglycolic acid, dithioglycolic acid and mercapto compounds such as ammonium thioglycolate, glyceryl, monothioglycolate, mercapto propionic acid and mercapto ethyl amine are most often employed in professional waving or hair straightening. Alkaline sulfites and bisulfites are generally reserved for home permanent use. In addition to the reducing agent, alkalis having a dissociation constant less than 5.times.10.sup.-3, are also used to facilitate diffusion through the hair. These promotors include ammonia, ammonium hydroxide, ethanol amine, diisopropanol amine, glycine, and lysine.
In an attempt to minimize these harmful effects polymeric quaternized amines have been developed as reducing agent supports, e.g. see U.S. Pat. No. 4,579,732. These basic compounds have not been found to be completely satisfactory for the reason that they react with anionic PG,5 components which are often present in hair structure altering compositions. Additionally the terminal amino groups react with hydrogen peroxide to form nitrogen oxides, thus increasing the effective amounts of peroxide which must be employed in fixing solutions. Since peroxides are known to have a hair drying effect, it is desirable to maintain the peroxide at a minimum level. In addition the large molecular size of these polymeric products prevents their penetration into the hair fiber and instead forms a coating over the hair which is subject to tack under conditions of high humidity. Further, many reducing lotions produce a disagreeable odor during reduction of the cystine molecule which the polymeric amines are unable to overcome. Finally, the relatively high viscosity of these quaternized polymers together with the normal variations in molecular weight in the polymer chains in the product lead to formulation problems in reproducability of product quality and in storage of the product over extended periods.
All of the commercial reducing lotions cause some degree of hair damage depending on the tightness and thickness of the curl, the temperature of processing, the concentration of the alkaline reducing agent and the condition of the hair. Accordingly, the art continues to seek means and possibilities whereby to provide for the aforesaid waving and straightening lotions, compositions which are less damaging to the skin and hair and which contain stable components simple to incorporate into the standard reducing lotions currently in use so as to provide the same or more effective results for heat or cold permanent waving and hair straightening. One method for the realization of these objects can be achieved by promoting penetration of the reducing lotion and providing absorption at a faster rate so that the time hair fiber is exposed to chemical action is reduced.
Secondary aims for permanent waving compositions include masking the thiol odor of the reducing lotion, providing non-degradable compounds which may be easily and reproduceably formulated and minimizing skin irritation caused by routine exposure of professional hair dressers or erythema on the scalp and neck of the subject undergoing treatment.
In regard to hair color, the main coloring component is a dark pigment, melanin, which occurs as granules embedded in the hair cortex. The aim of bleaching is to decolorize selectively the natural pigments or applied pigments in the hair with minimal damage to the hair matrix. When hair is bleached, the color changes to lighter and lighter shades depending upon the amount of melanin granules dissolved and removed from the hair fiber. Hydrogen peroxide is the leading solvent for melanin used in the bleaching process; however, along with melanin removal, the peroxide reacts with keratin to cause loss of tensile properties and damage to the hair. More specifically, bleaching occurs in two steps: (1) initial solubilization of the color granules, and (2) decolorization of the dark brown solubilized pigment. The reaction between melano-protein and hydrogen peroxide is confined mainly to the protein-combined cystine residues which are subsequently converted to combined cysteic acid. The solubilization of the melanin granules is connected with the splitting of the disulfide bridges in the melano protein and it is likely that the disulfide bridge may be the stabilizing factor in melanin, as it is in keratins.
The bleaching process can be halted at any point or can be permitted to continue to a light blonde or platinum shade. The latter provides a good background for a variety of tints which can be obtained by a subsequent coloring step. Such bleaching and coloring combination is known as a double process coloring and causes hair damage by promoting porosity, brittleness, loss of tensile strength and dryness.
Permanent hair colorants involve the use of oxidation dye intermediates which are colorless substances but which, when mixed with oxidizing agents just prior to use, produce color by a process of oxidative condensation. More specifically, the intermediates, in the presence of an oxidant, couple with another oxidation dye intermediate molecule to form a large fused ring color compound within the hair fiber. Since the fused ring product is too large to penetrate the hair fiber, it is essential that good penetration is achieved by the precursor intermediate. The oxidation dye process engenders many changes in the chemical and cosmetic characteristics of the hair which are undesirable. Specifically, the effect of alkali swelling of the hair fiber leads to loss of tensile strength, flexibility and promotes a porous, dry appearance. Additionally, the oxidation dye intermediates often cause skin sensitivity and reddening. Still further, the color imparted on processed hair is often non-uniform since the preprocessed sections, have higher porosity and absorb the intermediate at a faster rate than virgin growth which is more resistant to absorption.
Certain quaternized amine compounds and polymeric amines as disclosed in U.S. Pat. Nos. 4,532,127 and 4,579,732 have been developed to overcome some of the above problems. However these basic compounds have not been found to be completely satisfactory since they react with anionic components which are commonly present in hair coloring or bleaching compositions. This reactivity causes undesirable alterations in the shade desired. Additionally the amino groups react with hydrogen peroxide to form nitrogen oxides, thus increasing the effective amount of peroxide which must be employed in bleaching compositions. Since peroxides are known to have a drying effect on hair, it is desirable to use as little as possible to obtain the desired effect. Further the relatively high viscosity of the polymeric compounds together with the normal variation in molecular weight of the polymer chains in the product lead to formulation problems in reproducibility of product quality and in storage of the product over extended periods. In addition the large molecular size of the polymeric products prevents their penetration into the hair fiber and instead forms a coating over the hair, which may develop tack under conditions of high humidity. Finally, many hair dye and bleaching compositions produce a disagreeable odor which the prior quaternized amino compounds do not mask.
Accordingly, it is an object of this invention to achieve the various aims enumerated above by a simple and commercially feasible process involving the addition of the compound of the present invention as a component in standard hair processing or treating formulations, including structure altering, color altering, shampooing and conditioning formulations, used both professionally and at home.
Another object of the invention is to provide an additive to hair reducing lotions which promotes a higher degree of curl in a shorter period of time.
Another object of the invention is to provide an additive which actually conditions the hair undergoing a color altering or restructuring treatment or other cosmetic treatments.
Another object is to provide a compound which, when added to a hair coloring, hair bleaching, hair waving or straightening lotion, increases the penetration rate of the lotion to minimize run-off and dripping.
Yet another object is to provide a long lasting processing affect that moisturizes and protects the hair fiber so as to give the processed hair a silky softness.
Still another object is to provide an additive which improves hard water solubility of components in various hair processing lotions.
Still another object is to provide a non-polymeric compound of reproduceable composition which is substantially non-reactive with respect to anionic components and hydrogen peroxide and which is stable under conditions of high humidity.
Yet another object of this invention to overcome or minimize the deficiencies of prior hair preparations by providing a chemically stable additive which obviates skin sensitization, conditions the hair during processing, aids in the penetration of dye intermediate without undue alkaline swelling of the hair fiber, provides complexing sites on which the colorant can form, minimizes the period of hair exposure to chemical solutions, provides a more uniform distribution of color to processed hair by promoting penetration in portions of new hair growth, preserves the tensile properties of bleached or dyed hair, improves curl retention and successfully masks undesirable thiol odors.
These and other objects of the invention will become apparent from the following description and disclosure.